Objective. To estimate the prevalence of alarm symptoms for breast, colorectal, urinary tract, and lung cancer in the general population. Design. Cross-sectional questionnaire survey. Setting. The former County of Funen, Denmark, with 480 000 inhabitants. Participants. A total of 13 777 randomly selected persons aged 20 years and older. Main outcome measures. Prevalence estimates of having experienced cancer alarm symptoms during the past 12 months: a lump in the breast, blood in bowel movements, blood in urine, or coughing for more than six weeks. The number of alarm symptoms experienced within the past 12 months was also calculated. Results. With a response rate of 69%, 3.3% of responders (95% CI 2.9% to 3.7%) reported a lump in their breast, 5.7% (5.2% to 6.3%) reported blood in bowel movements, 2.2% (1.9% to 2.5%) reported blood in urine, and 6.5% (6.1% to 7.5%) reported coughing for more than six weeks within the past 12 months. Overall, 15.3% (95% confidence interval 14.3% to 16.3%) of the females and 12.7% (11.6% to 13.7%) of the males reported having experienced at least one cancer alarm symptom within the past 12 months. Conclusion. Alarm symptoms of breast, colorectal, urinary tract, and lung cancer are common in the general population and approximately 15% of the population have experienced at least one of these cancer alarm symptom within the past 12 months.